UV curable paint compostions and method of making and applying same

ABSTRACT

The present invention discloses an ultraviolet light curable paint composition and method for applying and making such a composition to a substrate. Suitable substrates include glass, metals, and various plastics such as polycarbonates. The disclosed composition does not contain any significant amount of volatile organic solvents that do not become incorporated in the coating or are released to ambient after curing.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. applicationSer. No. 09/669,055 filed Sep. 25, 2000, which, in turn, claims thebenefit of U.S. Provisional Application Serial No. 60/163,875, filedNov. 5, 1999.

TECHNICAL FIELD

[0002] The present invention relates to ultraviolet light (UV) curablepaint compositions capable of producing coating with enhanced corrosionand weathering resistance; and in particular to UV curable compositionscapable of producing paint coatings on a substrate.

BACKGROUND OF THE INVENTION

[0003] UV radiation curable paint compositions are applied to asubstrate through spraying, screen printing, dipping or brushing for theprotection or decoration of the substrate. In the usual application, asubstrate such as metal, glass, or plastic is coated with the paintcomposition and then UV light is introduced to complete the curingprocess. The UV curable paint compositions offer many advantages overtypical heat curable compositions.

[0004] Heat curable compositions require the use of organic solventsthat contain a significant amount of volatile organic compounds (VOCs).These VOCs escape into the atmosphere while the heat curable compositiondries. Such solvent based systems are undesirable because of the hazardsand expenses associated with VOCs. The hazards include water and airpollution and the expenses include the cost of complying with strictgovernment regulation on solvent emission levels. In contrast, UVcurable compositions contain reactive monomers instead of solvents; thuseliminating the detrimental effects of the VOCs.

[0005] Although, the use of heat curable compositions raisesenvironmental concerns, other disadvantages exist with their use aswell. Heat curable compositions suffer from slow cure times which leadto decreased productivity. These compositions require high energy forcuring due to energy loss as well as the energy required to heat thesubstrate. Additionally, many heat curable compositions yield poor filmproperties that result in decreased value of the end product.

[0006] Although UV curable compositions exhibit superior properties andperformance over their heat curable counterparts, UV curablecompositions themselves suffer from certain disadvantages. Generally, UVcompositions have high molecular weights and a substantial degree ofcross linkage due to the highly reactive nature of the composition. As aresult, many of these compositions suffer from low durability and resinshrinkage. With the use of many such compositions, an inordinately highamount of UV light is required to cure. New formulations that lessenthese problems typically suffer from diminished abrasion, chemical, andscratch resistance as well as low thermal stability and adhesion.

[0007] An additional disadvantage of typical UV compositions is theirlack of stability which results in dispersion. With some compositions,suspended solids fall out of solution after a period of one to two days.Dispersion adversely affects the gloss and clarity of the finishedproduct. To combat this problem, new compositions have been formulatedwith higher viscosities which often lessen the flowability of thecomposition. These viscous formulations rule out spray application andprovide for an unsuitably high dipping thickness.

[0008] Accordingly, there exists a need to provide environmentally safeUV curable paint compositions which exhibit improved appearance,weatherability, corrosion resistance and workability. Additionally,there is a need to provide a method of applying an improved compositionwhich furthers the goal of improved performance.

SUMMARY OF INVENTION

[0009] It is an object of the present invention to provide an improvedpaint composition that is curable by ultraviolet light.

[0010] It is another object of the present invention to provide animproved paint composition that can be applied by spraying, screenprinting, dipping, and brushing.

[0011] It is yet another object of the present invention to provide animproved paint composition that is capable of protecting metal surfacesfrom chemical corrosion and weathering.

[0012] It is still another object of the present invention to provide animproved paint composition that can be used to coat the metal parts inthe undercarriage of an automobile.

[0013] It is still another object of the present invention to provide animproved paint composition that comprises at least one aliphaticacrylated oligomer that can be used to coat a metallic substrate suchthat no significant amount of volatile organic solvents do not becomeincorporated in the coating after the composition is cured.

[0014] The present invention discloses an ultraviolet light curablepaint composition and method for making such a composition that may beused to produce a paint coating on a substrate. The disclosedcomposition does not contain any significant amount of volatile organicsolvents that do not become incorporated in the coating after curing.Specifically, the paint composition contains 5% or less volatile organicsolvents by weight. The disclosed invention provides a paint compositionthat is capable of protecting metal parts from chemical corrosion andweathering. In particular, automobile undercarriage components that arecoated with the disclosed paint composition and then cured withultraviolet light experience improved protection from the harmfuleffects of salt and adverse weather conditions. Further, the cured paintcomposition produces a coating with improved appearance and withimproved resistance to rubbing off. Automobile undercarriage componentsinclude, but are not limited, to suspension swing arms, coil springbrackets, suspension stabilizers, frames, axles, and brake arms. Thedisclosed invention allows these automobile components to be coated moreeconomically than the standard electronic primer coat basecoat andpowder coat that is traditionally used in coating automobileundercarriage components.

[0015] In accordance with one aspect of the invention, an ultravioletlight curable paint composition is provided. The paint compositioncomprises a mixture of one or more aliphatic acrylated oligomers,wherein the aliphatic acrylated oligomer mixture is present in an amountof about 8% to 60% of the paint composition. All percentages of thepaint composition as expressed in this document refer to the weightpercentage of the stated component to the total weight of the paintcomposition.

[0016] The paint composition preferably further comprises an isobornylacrylate monomer in an amount of about 20% to 60% of the paintcomposition, a photoinitiator in an amount of about 1% to 16% of thepaint composition, a pigmented composition in an amount of 0% to 50%, anoptional flow promoting agent in an amount of about 0.1% to 6% of thepaint composition, and an optional adhesion promoter in an amount of 1%to 12%.

[0017] In accordance with yet another aspect of the invention, a methodis provided for depositing or applying a paint coating on a substrate.The method comprises a first step of applying to the substrate apaint-containing fluid-phase composition (“paint composition”). Suitablemethods of applying the paint composition to the substrate includespraying, screen-printing, dipping, and brushing. The paint compositioncomprises a mixture of aliphatic acrylated oligomers, wherein thealiphatic acrylated oligomer is present in an amount of about 8% to 60%of the paint composition. The paint composition also includes anisobornyl acrylate monomer in an amount of about 20% to 60% of the paintcomposition, a photoinitiator in an amount of about 1% to 16% of thepaint composition, a flow promoting agent in an amount of about 0.1% to6% of the paint composition, a pigmented composition in an amount of 0%to 50% of the paint composition, and optionally an adhesion promoter inan amount of 1% to 12%.

[0018] The method also includes a second step of illuminating the paintcomposition on the substrate with an ultraviolet light to cause thepaint composition to cure into the paint coating.

[0019] In accordance with this method, the paint composition can beselectively deposited on the substrate at specific locations where paintplating is desired. The paint composition need not be applied to theentire substrate.

BEST MODE FOR CARRYING OUT THE INVENTION

[0020] Paint Compositions

[0021] Reference will now be made in detail to presently preferredcompositions or embodiments and methods of the invention, whichconstitute the best modes of practicing the invention presently known tothe inventor.

[0022] The term “alkyl” means a straight or branched hydrocarbon radicalhaving from 1 to 12 carbon atoms and includes, for example, methyl,ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, undecyl,dodecyl, and the like.

[0023] The term “cycloalkyl” means a saturated hydrocarbon ring whichcontains from 3 to 20 carbon atoms, for example, cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, isobornyl, and the like.Cycloalkyl also includes multicycyclic groups such as bicyclic andtricyclic alkyl groups.

[0024] The term “cycloalkenyl” means hydrocarbon ring having at leastone unsaturation which contains from 5 to 20 carbon atoms. Cycloalkenylalso includes multicycyclic groups such as bicyclic and tricyclic groupshaving at least one unsaturation.

[0025] The terms “alkoxy” and “thioalkoxy” are O-alkyl or S-alkyl asdefined above for alkyl.

[0026] The term “aryl” means an aromatic radical. Example of arylinclude a phenyl group, a naphthyl group, a phenyl group substituted by1 to 4 substituents selected from alkyl as defined above, alkoxy asdefined above, thioalkoxy as defined above, hydroxy, halogen,trifluoromethyl, amino, alkylamino as defined above for alkyl,dialkylamino as defined for alkyl, N-acetylamino, cyano —SO₂NH₂, ornitro, or a naphthyl group substituted by 1 to 4 substituents as definedabove for a phenyl group substituted by 1 to 4 substituents.

[0027] The term “acrylated aliphatic oligomer” means acrylic acrylates,amine modified polyether acrylates, chlorinated polyester acrylates,melamine acrylates, polybutadiene acrylates, polyester acrylates,polyether acrylates, and urethane acrylates that do not contain an arylgroup. Epoxy acrylates, silicon acrylates, and fluorinate acrylates arenot included in the definition of acrylated aliphatic oligomer.

[0028] In accordance with one aspect of the invention, a presentlypreferred ultraviolet light curable paint composition (“paintcomposition”) is provided. In this preferred embodiment, the paintcomposition includes a mixture of aliphatic acrylated oligomers. Thealiphatic acrylated oligomer mixture is present in an amount of about 8%to 60% of the paint composition. If the paint composition is applied byspraying, the aliphatic acrylated oligomer mixture is more preferablypresent in an amount of about 30% to 55%, and most preferably about 45%.If the paint composition is applied by screen printing, the aliphaticacrylated oligomer mixture is more preferably present in an amount ofabout 8% to 60%, and most preferably about 50%. The aliphatic acrylatedoligomer preferably comprises one or more urethane oligomers. Suitablealiphatic acrylated oligomers include Radcure Ebecryl 244 (aliphaticurethane diacrylate diluted 10% with 1,6-hexanediol diacrylate), Ebecryl264 (aliphatic urethane triacrylate diluted 15% with 1,6-hexanedioldiacrylate), Ebecryl 284 (aliphatic urethane diacrylate diluted 10% with1,6-hexanediol diacrylate) commercially available from Radcure UCB Corp.of Smyrna, Ga.; Sartomer CN-961E75 (aliphatic urethane diacrylateblended with 25% ethoxylated trimethylol propane triacylate), CN-961H81(aliphatic urethane diacrylate blended with 19% 2(2-ethoxyethoxy)ethylacrylate), CN-963A80 (aliphatic urethane diacrylate blended with 20%tripropylene glycol diacrylate), CN-964 (aliphatic urethane diacrylate),CN-966A80 (aliphatic urethane diacrylate blended with 20% tripropyleneglycol diacrylate), CN-982A75 (aliphatic urethane diacrylate blendedwith 25% tripropylene glycol diacrylate) and CN-983 (aliphatic urethanediacrylate), commercially available from Sartomer Corp. of Exton, Pa.;TAB FAIRAD 8010, 8179, 8205, 8210, 8216, 8264, M-E-15, UVU-316,commercially available from TAB Chemicals of Chicago, Ill.; and EchoResin ALU-303, commercially available from Echo Resins of Versaille,Mo.; and Genomer 4652, commercially available from Rahn Radiation Curingof Aurora, Ill. The preferred aliphatic acrylated oligomers includeEbecryl 264 and Ebecryl 284. Ebecryl 264 is an aliphatic urethanetriacrylate of 1200 molecular weight supplied as an 85% solution inhexanediol diacrylate. Ebecryl 284 is aliphatic urethane diacrylate of1200 molecular weight diluted 10% with 1,6-hexanediol diacrylate.Combinations of these materials may also be employed herein.

[0029] The paint composition of the present invention also preferablyincludes an ethylenically unsaturated monomer having Formula I:

[0030] wherein R₁ is hydrogen or substituted or unsubstituted alkyl(i.e., optionally substituted alkyl); and R₂ is substituted orunsubstituted alkyl having more than 4 carbon atoms, cycloalkyl,cycloalkenyl, or substituted or unsubstituted aryl. Preferably R₁ ishydrogen or methyl; and R₂ is isoborynl, phenyl, benzyl,dicylcopentenyl, diclypentenyl oxyethyl, cyclohexyl, and naphthyl. Themost preferred ethyleneically unsaturated monomers are isobornylacrylate monomers. The isobornyl acrylate monomer is preferably presentin an amount of about 20% to 60% of the paint composition. If the paintcomposition is applied by spraying, the isobornyl acrylate monomer ismore preferably present in an amount of about 20% to 50%, and mostpreferably about 27%. If the paint composition is applied by screenprinting, the isobornyl acrylate monomer is more preferably present inan amount of about 20% to 60%, and most preferably about 31%. Suitableisobornyl acrylate monomers include Sartomer SR423 (isobornylmethacrylate):

[0031] and SR506 (isobornyl acrylate):

[0032] available from Sartomer Corp.; Radcure IBOA (isobornyl acrylate),commercially available from Radcure Corp.; IBOA and IBOMA, commerciallyavailable from CPS Chemical of Bradford, England; and Genomer 1121,commercially available from Rahn Radiation Curing. The preferredisobornyl acrylate monomer is Radcure IBOA, commercially available fromRadcure Corp. Radcure IBOA is a high purity, low color monomer.Combinations of these materials may also be employed herein.

[0033] The preferred paint composition also preferably includes apigmented composition in an amount of about 0% to 50% of the paintcomposition. If the paint composition is applied by spraying, thepigmented composition is more preferably present in an amount of about1% to 20%, and most preferably about 4%. If the paint composition isapplied by screen printing, the pigmented composition is more preferablypresent in an amount of about 1% to 50%, and most preferably about 2%.Suitable pigmented compositions include Venus #91 pigment and Palegold#400 available from NazDar of Atlanta, Ga.; BB 1355,ST8703, ST 8657, andST 8003 available from ElementisSpecialties of Jersey City, N.J.;Tint-AYD PC 9003 Titanium Dioxide available from Daniel Products Companyof Jersey City, N.J., and Al #200 pigment available from Silberline ofLeven, England. The preferred pigment used will depend on the desiredcolor of the paint. For example, if a black paint composition isdesired, BB 1355 is the preferred pigment. If the pigment is omittedfrom the composition, a clear paint composition is obtained.Combinations of these materials may also be employed herein.

[0034] This preferred paint composition also includes a photoinitiatorin an amount of about 1% to 16% of the paint composition. If the paintcomposition is applied by spraying, the photoinitiator is morepreferably present in an amount of about 3% to 12%, and most preferablyabout 10%. If the paint composition is applied by screen printing, thephotoinitiator is more preferably present in an amount of about 2% to16%, and most preferably about 4%. Suitable photoinitiators includeIrgacure 184 (1-hydroxycyclohexyl phenyl ketone),

[0035] available commercially from Ciba-Geigy Corp., Tarrytown, N.Y.;CYRACURE UVI-6974 (mixed triaryl sulfonium hexafluoroantimonate salts)and cyracure UVI-6990 (mixed triaryl sulfonium hexafluorophosphatesalts) available commercially from Union Carbide Chemicals and PlasticsCo. Inc., Danbury, Conn.; and Genocure CQ, Genocure BOK, and GenocureM.F., commercially available from Rahn Radiation Curing. The preferredphotoinitiator is Irgacure 1700 commercially available from Ciba-Geigyof Tarrytown, N.Y. Combinations of these materials may also be employedherein.

[0036] The preferred paint composition may optionally include a flowpromoting agent in an amount of about 0.1% to 6% of the paintcomposition. If the paint composition is applied by spraying, the flowpromoting agent is more preferably present in an amount of about 2% to6%, and most preferably about 5%. If the paint composition is applied byscreen printing, the flow promoting agent is more preferably present inan amount of about 1% to 5%, and most preferably about 4%. Suitable flowpromoting agents include Genorad 17, commercially available from RahnRadiation Curing; and Modaflow, commercially available from MonsantoChemical Co., St. Louis, Mo. The preferred flow promoting agent isModaflow which is an ethyl acrylate and 2-ethylhexyl acrylate copolymerthat improves the flow of the composition. Combinations of thesematerials may also be employed herein.

[0037] The preferred paint composition may optionally include anadhesion promoter in an amount of about 1% to 12% of the paintcomposition. If the paint composition is applied by spraying, theadhesion promoter is more preferably present in an amount of about 1% to11%, and most preferably about 9%. If the paint composition is appliedby screen printing, the adhesion promoter is more preferably present inan amount of about 4% to 11% and most preferably about 9%. Suitableadhesion promoters include Ebecryl 168 (methacrylated acidic adhesionpromoter), commercially available from Radcure Corp.; and Sartomer CN704 (acrylated polyester adhesion promoter) and CD 9052 (trifunctionalacid ester), commercially available from Sartomer Corp. The preferredadhesion promoter is Ebecryl 168 which is a methacrylated acidicadhesion promoter. Combinations of these materials may also be employedherein.

[0038] To illustrate, the following example sets forth a presentlypreferred paint composition according to this aspect of the invention.

EXAMPLE 1

[0039] This example provides a preferred paint composition according tothe invention that can be used for applying a black paint coating to asubstrate preferably by either spray or flexographic techniques.Suitable substrates include cast iron and other metals. The paintcomposition was made from the following components: ApproximateComponent Weight % Ebecryl 264 22.5 Ebecryl 284 22.5 IBOA 27.1 Ebecryl168 9.1 Modaflow 4.5 Irgacure 1700 10.4 Black BB1355 3.9 Total 100.00

[0040] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the BB 1355 is introduced into the pan and mixed for 1 to 2minutes at a speed of 2000 rpm. The temperature during mixing ismonitored. The mixing is temporarily suspended if the temperatureexceeds 100° F.

EXAMPLE 2

[0041] This example provides a preferred paint composition according tothe invention that can be used for applying a black paint coating to asubstrate preferably by a spray technique. Suitable substrates includecast iron and other metals. The paint composition was made from thefollowing components: Approximate Component Weight % Ebecryl 264 16.1Ebecryl 284 16.1 IBOA 47.9 Ebecryl 168 6.5 Modaflow 3.2 Irgacure 17007.4 Black BB1355 2.8 Total 100.00

[0042] In this example, the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the BB 1355 is introduced into the pan and mixed for 1 to 2minutes at a speed of 2000 rpm. The temperature during mixing ismonitored. The mixing is temporarily suspended if the temperatureexceeds 100° F.

EXAMPLE 3

[0043] This example provides a preferred paint composition according tothe invention that can be used for applying a green paint coating to asubstrate preferably by screen printing. Suitable substrates includemetals and polycarbonates. The paint composition was made from thefollowing components: Approximate Component Weight % Ebecryl 264 23.1Ebecryl 284 26.8 IBOA 31.2 Ebecryl 168 8.9 Modaflow 3.6 Irgacure 17004.4 Green ST8703 2.0 Total 100.00

[0044] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the Green ST8703 pigment is introduced into the pan andmixed for 1 to 2 minutes at a speed of 2000 rpm. The temperature duringmixing is monitored. The mixing is temporarily suspended if thetemperature exceeds 100° F.

EXAMPLE 4

[0045] This example provides a preferred paint composition according tothe invention that can be used for applying a orange paint coating to asubstrate preferably by screen printing. Suitable substrates includemetals and polycarbonate. The paint composition was made from thefollowing components: Approximate Component Weight % Ebecryl 264 23.1Ebecryl 284 26.8 IBOA 31.2 Ebecryl 168 8.9 Modaflow 3.6 Irgacure 17004.4 Orange ST8657 2.0 Total 100.00

[0046] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the Orange ST8657 pigment is introduced into the pan andmixed for 1 to 2 minutes at a speed of 2000 rpm. The temperature duringmixing is monitored. The mixing is temporarily suspended if thetemperature exceeds 100° F.

EXAMPLE 5

[0047] This example provides a preferred paint composition according tothe invention that can be used for applying a clear paint coating to asubstrate preferably by spray or flexographic techniques. Suitablesubstrates include glass, metals, and polycarbonate. The paintcomposition was made from the following components: ApproximateComponent Weight % Ebecryl 264 22.7 Ebecryl 284 19.7 IBOA 43.2 Ebecryl168 7.6 Modaflow 3.0 Irgacure 1700 3.8 Total 100.00

[0048] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the final step, the Ebecryl 168 adhesion promoteris introduced into the pan and mixed for 1 to 2 minutes at a speed of2000 rpm. The temperature during mixing is monitored. The mixing istemporarily suspended if the temperature exceeds 100° F.

EXAMPLE 6

[0049] This example provides a preferred paint composition according tothe invention that can be used for applying a metallic copper-coloredpaint coating to a substrate preferably by screen printing. Suitablesubstrates include metals and polycarbonates. The paint composition wasmade from the following components: Approximate Component Weight %Ebecryl 264 27.9 Ebecryl 284 16.9 IBOA 22.2 Ebecryl 168 4.1 Modaflow 3.1Irgacure 1700 5.3 Palegold #400 20.5 pigment (copper) Total 100.00

[0050] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the Palegold #400 pigment is introduced into the pan andmixed for 1 to 2 minutes at a speed of 2000 rpm. The temperature duringmixing is monitored. The mixing is temporarily suspended if thetemperature exceeds 100° F.

EXAMPLE 7

[0051] This example provides a preferred paint composition according tothe invention that can be used for applying a metallic aluminum-coloredpaint coating to a substrate preferably by screen printing. Suitablesubstrates include metals and polycarbonates. The paint composition wasmade from the following components: Approxmiate Component Weight %Ebecryl 264 20.0 Ebecryl 284 20.0 IBOA 24.0 Ebecryl 168 8.0 Modaflow 4.0Irgacure 1700 4.0 A1 #200 pigment 20.0 Total 100.00

[0052] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the Al #200 pigment is introduced into the pan and mixed for1 to 2 minutes at a speed of 2000 rpm. The temperature during mixing ismonitored. The mixing is temporarily suspended if the temperatureexceeds 100° F.

EXAMPLE 8

[0053] This example provides a preferred paint composition according tothe invention that can be used for applying a metallic gold-coloredpaint coating to a substrate preferably by screen printing. Suitablesubstrates include metals and polycarbonates. The paint composition wasmade from the following components: Approximate Component Weight %Ebecryl 264 10.5 Ebecryl 284 10.5 IBOA 22.5 Ebecryl 168 4.2 Modaflow 2.2Irgacure 1700 3.9 Venus #91 46.2 pigment Total 100.00

[0054] In this example the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the Venus #91 pigment is introduced into the pan and mixedfor 1 to 2 minutes at a speed of 2000 rpm. The temperature during mixingis monitored. The mixing is temporarily suspended if the temperatureexceeds 100° F.

EXAMPLE 9

[0055] This example provides a preferred paint composition according tothe invention that can be used for applying a white colored paintcoating to a substrate preferably by screen printing. Suitablesubstrates include metals and polycarbonates. The paint composition wasmade from the following components: A. B. C. Approximate ApproximateApproximate Component Weight % Weight % Weight % Ebecryl 264 4.9 7.812.0 Ebecryl 284 4.3 6.8 10.4 IBOA 46.7 53.0 40.0 Ebecryl 168 2.1 2.53.1 Modaflow 1.5 2.4 2.6 Irgacure 1700 6.7 10.7 14.1 ST8003 33.8 16.817.8 white pigment Total 100.00 100.00 100.00

[0056] In this example, the IBOA and Irgacure 1700 are mixed in a panwith a propeller blade mixer for 30 seconds at a speed of 500 to 1000rpm. In the next step, the Ebecryl 264, the Ebecryl 284, and theModaflow are introduced into the pan and mixed for 1 to 2 minutes at aspeed of 2000 rpm. In the next step, the Ebecryl 168 adhesion promoteris added and mixed for 1 to 2 minutes at a speed of 2000 rpm. In thefinal step, the ST8003 pigment is introduced into the pan and mixed for1 to 2 minutes at a speed of 2000 rpm. The temperature during mixing ismonitored. The mixing is temporarily suspended if the temperatureexceeds 100° F.

[0057] Method for Depositing a Paint Coating on a Substrate

[0058] In accordance with still another aspect of the invention, amethod is provided for depositing a paint coating on a suitablesubstrate. The method comprises a first step of applying a fluid-phasecomposition (“paint composition”) to the substrate.

[0059] The paint composition comprises an aliphatic acrylated oligomermixture, the aliphatic acrylated oligomer mixture being present in anamount of about 8% to 60% of the paint composition; an isobornylacrylate monomer in an amount of about 20% to 60% of the paintcomposition; an photoinitiator in an amount of about 1% to 16% of thepaint composition; a flow promoting agent in an amount of about 0.1% to6% of the paint composition, a pigment containing composition in anamount of 0% to 50%, and optionally an adhesion promoter in an amount of1% to 12%. The preferred paint compositions according to this method arethose described herein, for example, including the compositionsdescribed in examples 1 through 9.

[0060] The paint composition may be applied to the substrate using anumber of different techniques. The paint composition may be applied,for example, by direct brush application, or it may be sprayed onto thesubstrate surface. If automobile undercarriage components are to becoated, the spray technique is particularly useful, in that thecomponents may be spray coated on a conveyorized system. The paintcomposition may also be applied using a screen printing technique. Insuch screen printing technique, a “screen” as the term is used in thescreen printing industry is used to regulate the flow of liquidcomposition onto the substrate surface. The paint composition typicallywould be applied to the screen as the latter contacts the substrate. Thepaint composition flows through the silk screen to the substrate,whereupon it adheres to the substrate at the desired film thickness.Screen printing techniques suitable for this purpose include knowntechniques, but wherein the process is adjusted in ways known to personsof ordinary skill in the art to accommodate the viscosity, flowability,etc. of the liquid-phase composition, and the substrate of surfaceproperties. Flexographic techniques using pinch rollers to contact thepaint composition with a rolling substrate may be used.

[0061] The method includes a second step of illuminating thepaint-containing fluid-phase composition on the substrate with anultraviolet light to cause the paint-containing fluid-phase compositionto cure into the paint coating. This illumination may be carried out inany number of ways, provided the ultraviolet light or radiation impingesupon the paint composition so that the paint composition is caused topolymerize to form the coating, layer, film, etc. If automotiveundercarriage components are to be coated, steps of coating thecomponents by spraying and illuminating the coated parts may besequentially performed in a conveyorized system.

[0062] Curing preferably takes place by free radical polymerization,which is initiated by an ultraviolet radiation source. Variousultraviolet light sources may be used, depending on the application.Preferred ultraviolet radiation sources for a number of applicationsinclude known ultraviolet lighting equipment with energy intensitysettings of, for example, 125 watts, 200 watts, and 300 watts per squareinch.

[0063] Additional advantages and modifications will readily occur tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details, representative devices,and illustrative examples shown and described. Accordingly, departuresmay be made from such details without departing from the spirit or scopeof the general inventive concept.

[0064] While embodiments of the invention have been illustrated anddescribed, it is not intended that these embodiments illustrate anddescribe all possible forms of the invention. Rather, the words used inthe specification are words of description rather than limitation, andit is understood that various changes may be made without departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A method for coating a substrate with a paint composition, the method comprising, a) applying the paint composition to the substrate, wherein the paint composition includes: an aliphatic acrylated oligomer mixture; an ethylenically unsaturated monomer having Formula I:

 wherein R₁ is hydrogen or an optionally substituted alkyl; and R₂ is substituted or unsubstituted alkyl having more than 4 carbon atoms, cycloalkyl, cycloalkenyl, or substituted or unsubstituted aryl; a pigmented material; and a photoinitiator; and b) illuminating the paint composition on the metallic substrate with an UV light sufficient to cause the paint composition to cure into the paint coating.
 2. The method of claim 1 wherein R₁ is hydrogen or methyl; and R₂ is isoborynl, phenyl, benzyl, dicylcopentenyl, diclypentenyl oxyethyl, cyclohexyl, and naphthyl.
 3. The method of claim 1 wherein the ethylenically unsaturated monomer is an isobornyl acrylate monomer.
 4. The method of claim 1 wherein the ethylenically unsaturated monomer is isobornyl methacrylate or isobornyl acrylate.
 5. The method of claim 3 wherein: the aliphatic acrylated oligomer mixture in an amount of about 8% to 60% of the weight of the paint composition; the isobornyl acrylate monomer in an amount of about 20% to 60% of the weight of the paint composition; the pigmented material in an amount of about 0% to 50% of the weight of the paint composition; and the photoinitiator in an amount of about 1% to 16% of the weight of the paint composition.
 6. The method of claim 5 wherein the paint composition further comprises: an adhesion promoter in an amount of about 1% to 12% of the weight of the paint composition; and a flow promoting agent in an amount of about 0.1% to 6% of the weight of the paint composition.
 7. The method of claim 6 wherein the method of applying the paint composition is spraying.
 8. The method of claim 7 wherein the paint composition includes: an aliphatic acrylated oligomer mixture in an amount of about 30% to 55% of the weight of the paint composition; an isobornyl acrylate monomer in an amount of about 20% to 50% of the weight of the paint composition; an adhesion promoter in an amount of about 4% to 11% of the weight of the paint composition; a pigmented material in an amount of about 1% to 20% of the weight of the paint composition; a photoinitiator in an amount of about 3% to 12% of the weight of the paint composition; and a flow promoting agent in an amount of about 2% to 6% of the weight of the paint composition.
 9. The method of claim 8, wherein, the aliphatic acrylated oligomer mixture is about 45% of the weight of the paint composition; the isobornyl acrylate monomer is about 27% of the weight of the paint composition; the adhesion promoter is about 9% of the weight of the paint composition; the pigmented material is about 4% of the weight of the paint composition; the photoinitiator is about 10% of the weight of the paint composition; and the flow promoting agent is about 5% of the weight of the paint composition.
 10. The method of claim 6 wherein the method of applying the paint composition is screen-printing.
 11. The method of claim 10 wherein the paint composition includes: an aliphatic acrylated oligomer mixture in an amount of about 8% to 60% of the weight of the paint composition; an isobornyl acrylate monomer in an amount of about 20% to 60% of the weight of the paint composition; an adhesion promoter in an amount of about 1% to 11% of the weight of the paint composition; a pigmented material in an amount of about 1% to 50% of the weight of the paint composition; a photoinitiator in an amount of about 2% to 16% of the weight of the paint composition; and a flow promoting agent in an amount of about 1% to 5% of the weight of the paint composition.
 12. The method of claim 11 wherein, the aliphatic acrylated oligomer mixture is about 50% of the weight of the paint composition; the isobornyl acrylate monomer is about 31% of the weight of the paint composition; the adhesion promoter is about 9% of the weight of the paint composition; the pigmented material is about 2% of the weight of the paint composition; the photoinitiator is about 4% of the weight of the paint composition; and the flow promoting agent is about to 4% of the weight of the paint composition.
 13. The method of claim 1, wherein the UV light used in illuminating impinges upon the paint composition so that the paint composition is caused to form the coating as it cures.
 14. The method of claim 1, wherein the method of applying the paint composition is dipping the substrate into the composition sufficiently to cause the composition to uniformly coat the substrate.
 15. The method of 1, wherein the method of applying the paint composition is brushing.
 16. The method of 1, wherein the method of applying the paint composition is selectively depositing to the substrate at predetermined locations.
 17. A coated substrate made by the method comprising: a) applying a paint composition to the substrate, wherein the paint composition includes: an aliphatic acrylated oligomer mixture; an isobornyl acrylate monomer; a pigmented material; and a photoinitiator; and b) illuminating the paint composition on the metallic substrate with an UV light sufficient to cause the paint composition to cure into the paint coating.
 18. The coated substrate of claim 17 wherein: the aliphatic acrylated oligomer mixture in an amount of about 8% to 60% of the weight of the paint composition; the isobornyl acrylate monomer in an amount of about 20% to 60% of the weight of the paint composition; the pigmented material in an amount of about 0% to 50% of the weight of the paint composition; and the photoinitiator in an amount of about 1% to 16% of the weight of the paint composition.
 19. The coated substrate of claim 18 wherein the paint composition further comprises: an adhesion promoter in an amount of about 1% to 12% of the weight of the paint composition; and a flow promoting agent in an amount of about 0.1% to 6% of the weight of the paint composition.
 20. The coated substrate of claim 19 wherein the method of applying the paint composition is spraying.
 21. The coated substrate of claim 20 wherein the paint composition includes: an aliphatic acrylated oligomer mixture in an amount of about 30% to 55% of the weight of the paint composition; an isobornyl acrylate monomer in an amount of about 20% to 50% of the weight of the paint composition; an adhesion promoter in an amount of about 4% to 11% of the weight of the paint composition; a pigmented material in an amount of about 1% to 20% of the weight of the paint composition; a photoinitiator in an amount of about 3% to 12% of the weight of the paint composition; and a flow promoting agent in an amount of about 2% to 6% of the weight of the paint composition.
 22. The coated substrate of claim 19 wherein the method of applying the paint composition is screen-printing.
 23. The coated substrate of claim 22 the paint composition includes: an aliphatic acrylated oligomer mixture in an amount of about 8% to 60% of the weight of the paint composition; an isobornyl acrylate monomer in an amount of about 20% to 60% of the weight of the paint composition; an adhesion promoter in an amount of about 1% to 11% of the weight of the paint composition; a pigmented material in an amount of about 1% to 50% of the weight of the paint composition; a photoinitiator in an amount of about 2% to 16% of the weight of the paint composition; and a flow promoting agent in an amount of about 1% to 5% of the weight of the paint composition.
 24. A method of preparing an ultraviolet (UV) curable paint composition comprising: a) combining an isobornyl acrylate monomer and a photoinitiator in a pan to form a first combination; b) mixing the first combination; c) combining an aliphatic acrylated oligomer mixture and a flow promoting agent, with the first mixture to form a second combination; d) mixing the second combination; e) combining an adhesion promoter with the second mixture to form a third combination; f) mixing the third combination; g) combining a pigment material with the second mixture to form a fourth combination; and h) mixing the fourth combination. 